GAF Underlayment & Deck Repair Nationwide

GAF Underlayment & Deck Repair: The Houston Owner’s Guide

GAF underlayment and deck repair in Houston typically runs $450 to $1,400 for a partial roof-area repair, and $1,800 to $4,600 when larger deck sections need replacement before new underlayment goes down. Most jobs are completed in one day once we’re on the roof. You’ll usually discover this problem the hard way: a shingle blows off after a storm, you go up to look, and the plywood underneath feels soft or the underlayment is torn, brittle, or gone in patches. Houston humidity accelerates underlayment failure faster than most climates in the country, especially on roofs where the previous contractor installed felt paper too thin for the heat we get between May and September.

Call (254) 566-3573

We’re an independent Houston roofing contractor, not affiliated with GAF itself, but we stock and install GAF-compatible underlayment and deck materials every week. Greg Holloway has walked more Meyerland and Oak Forest roofs with rotted decking than he can count, and the pattern is always the same: failed underlayment lets moisture sit on the sheathing, and once plywood starts delaminating, it doesn’t get better on its own.

Which GAF Models This Applies To

This repair applies to any GAF shingle system, but the compatibility question matters most on Timberline HDZ, Timberline UHDZ, and Royal Sovereign lines, which account for most of what we see across Houston. The key gotcha: GAF’s recommended underlayment spec depends on the shingle line. Timberline systems are rated for GAF Deck-Armor or FeltBuster synthetic underlayment, while some older Royal Sovereign installations still sit on 15 lb felt, which is exactly what fails first in our humidity. If you’re replacing underlayment, we always match the current GAF spec for that shingle rather than just reusing whatever the last guy stapled down.

OEM vs aftermarket gets simpler with underlayment than with mechanical parts. GAF Deck-Armor and FeltBuster are the OEM spec, but quality synthetic equivalents from Owens Corning and CertainTeed perform comparably and sometimes cost less. Tilehurst Roofing Houston stocks materials from all three, plus GAF, so we can price the job with the option you prefer. The part you see on the roof tells you most of the story: GAF shingles carry a label on the back of the shingle itself, and the underlayment type gets recorded on the original permit paperwork, which the City of Houston keeps on file for most addresses.

Signs Your GAF Underlayment & Deck Repair Is Failing

• Soft spots in the sheathing when you walk the roof. This means the deck plywood or OSB has absorbed enough moisture to lose structural strength. In Houston, this often shows up near valleys, hips, and around plumbing vents first, because those are the places water pools and sits longest.
• Interior water stains with no obvious shingle damage. The shingles can look fine from the ground while the underlayment underneath is doing all the failing. Water travels along the deck until it finds a seam or gap, then makes its way into the attic or ceiling.
• Shingles lifting or blowing off with underlayment still visible. When you can see the felt or synthetic layer under a missing shingle, UV exposure has already begun breaking it down. That exposed underlayment now has weeks, not months, before it starts leaking.
• Attic humidity spikes or visible mold growth on the underside of the decking. Underlayment is the last physical barrier between the shingles and the sheathing. When it fails, the decking holds moisture like a sponge, and Houston’s hotbox attics incubate mold quickly.
• Granules piling up in gutters, plus dampness at the ceiling. Worn shingles and failing underlayment often fail as a pair. The granules tell you the top layer is spent, but the moisture tells you the layer underneath has already given up.

Replacement Cost & What’s Included

Installed underlayment and deck repair in Houston breaks down like this: underlayment replacement alone runs $450 to $1,400 depending on roof size and pitch, decking repair adds $65 to $95 per 4×8 sheet replaced, and full sections of rotted deck rebuilt before new underlayment goes down run $1,800 to $4,600. Steep pitches drive the labor higher, as does a two-story roof where we’re hauling plywood on a ladder.

Every Tilehurst Roofing Houston estimate includes the written price before any work starts, the underlayment material by brand and name, deck sheets listed at a per-sheet rate, disposal of the old material, and our written guarantee on the repair. If the repair fails inside the guarantee period, our crew comes back at no charge under the 365-Day Done Right Promise. That’s not a premium add-on. It’s the floor.

DIY or Call Us?

A homeowner can safely check for failing underlayment by inspecting the attic for water stains on the underside of the decking, especially after the kind of heavy rain we get in April and May. What you shouldn’t do is pull up shingles and attempt to replace underlayment or sheathing yourself. The underlayment is glued, nailed, and sealed under shingles that have to come up in the right order, and if the deck needs replacement, you’re walking on compromised structure while moving plywood. Anyone doing this on a two-story Houston roof without the right equipment is one wet spot away from a bad afternoon.

If you’ve got soft decking, torn underlayment, or a leak that’s been diagnosed but never fixed right, call us at (254) 566-3573. You’ll know the price before we touch the roof.

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